KR20090010122A - Modified membrane - Google Patents

Abstract

A multilayered modified membrane and method for making the same, comprising a modified discriminating layer that can have a fouling resistant surface, improved salt rejection, antimicrobial properties, and/or improved solute, and/or small organics rejection as compared to membranes with unmodified discriminating layers.

Description

Modified membrane

Related Applications

This application claims the benefit of US Provisional Patent Application 60 / 799,863, filed May 12, 2006, which is incorporated herein by reference in its entirety.

The present invention generally relates to membranes and methods of making such membranes for use in separating liquid components. The membranes of the present invention are particularly useful for purifying water.

Reverse osmosis and nanofiltration membranes are used to separate dissolved or dispersed material from the feed stream. The separation process typically involves contacting an aqueous solution of the feed under pressure with one surface of the membrane to allow the aqueous phase to permeate through the membrane while preventing the permeation of dissolved or dispersed material as described above.

Both reverse osmosis and nanofiltration membranes comprise a thin film discriminating layer fixed to a porous support, commonly referred to collectively as a "composite membrane". Ultrafiltration and microfiltration membranes can also have a complex arrangement. The support provides physical strength but is slightly flow resistant due to the porosity of the support. Discriminating layers, on the other hand, provide the primary means of separating less porous and dissolved or dispersed materials. Thus, the separation layer generally comprises the "rejection rate" of the membrane provided, i.e. the percentage of removal of certain dissolved substances (e.g. solutes), and the "flux" i.e. solvent passes through the membrane. Flow rate per unit area).

Membrane manufacturers optimize the separator layer for the desired combination of solvent flow and solute removal, while also optimizing the porous support layer to provide pressure resistance and maximum strength combined with the minimum fluid resistance to be permeated. Theoretically, various chemical compositions can be molded into barrier thin layers, but only a few polymers provide a suitable combination for flow and solute removal resulting in a commercially good reverse osmosis or nanofiltration membrane. Reverse osmosis membranes and nanofiltration membranes differ from each other in terms of permeability to different ions and compounds.

Reverse osmosis membranes are relatively impermeable to virtually all ions, including sodium and chlorine ions. Thus, since the removal rate of sodium and chlorine ions relative to the reverse osmosis membrane is generally about 95 to about 100%, the reverse osmosis membrane is characterized by the use of salty water or seawater to provide relatively salt free water for industrial, commercial or domestic use. Widely used for desalination.

Nanofiltration membranes are generally more effective at removing ions including radium, magnesium, calcium, sulfates and carbonates. In addition, the nanofiltration membrane may be impermeable to organic compounds having a molecular weight greater than about 200 Daltons. In addition, the nanofiltration membrane may have a higher flow than the reverse osmosis membrane at comparable pressure. This feature is useful for various applications such as nanofiltration membranes "softening" water and removing pesticides from water. As an example, nanofiltration membranes may have a relatively high removal rate for salts such as magnesium sulfate and in some cases organic compounds such as atrazine, although sodium chloride removal is about 0 to about 95%.

Some membranes may be useful for reverse osmosis and nanofiltration applications by including a polyamide separator layer. Polyamide separator layers for reverse osmosis membranes are obtained by interfacial polycondensation reactions of polyfunctional amine monomers with polyfunctional acid halide monomers, as described, for example, in US Pat. No. 4,277,344. Polyamide separator layers for nanofiltration membranes can be piperazine, cyclohexane containing two or more reactive amines or aminoalkyl groups, or one or more reactive amine or aminoalkyl groups, as described in US Pat. Nos. 4,769,148 and 4,859,384. It can be obtained by interfacial polymerization of a piperidine containing a polyfunctional acid halide. Another method for obtaining a polyamide separator layer suitable for nanofiltration is by, for example, the methods described in US Pat. Nos. 4,765,897, 4,812,270 and 4,824,574. These patents describe converting reverse osmosis membranes into nanofiltration membranes, such as those of US Pat. No. 4,277,344.

Composite polyamide membranes can be prepared by coating a porous support with, for example, an aqueous solution with a polyfunctional amine monomer. Water is the preferred solvent, but non-aqueous solvents such as acetyl nitrile and dimethylformamide (DMF) can be used. The polyfunctional acid halide monomer may subsequently be coated on the support, for example with an organic solution. Although no specific order of addition is necessarily required, the amine solution may first be coated on the porous support and then the acid halide solution. One or both of the polyfunctional amine and the acid halide may be applied on the porous support as a solution, but they may also be applied by other means, such as by deposition or by neat.

Membrane fouling can occur due to attachment of suspended particles, scaling by insoluble salts, and bacterial contamination. While altering the polymer of the membrane can change properties such as permeability to various ions, membrane surface energy or membrane surface charge, this also requires a large change in membrane fabrication.

Membrane preparation can be carried out with dedicated equipment having an operating line of semi-continuous process. Introduction of membranes with new starting materials and membrane coating processes can be time-consuming and expensive. Using existing process lines and materials to produce a variety of different composite membranes may be less expensive.

Methods for improving the performance of membranes by adding components to amine and / or acid halide solutions are described in the literature. For example, US Pat. No. 4,950,404 to Chau discloses a flow through a composite membrane by adding a polar aprotic solvent and optional acid acceptor to an aqueous amine solution prior to interfacial polymerization of the amine with a polycarboxylic acid halide. It describes how to increase. Similarly, US Pat. No. 6,024,873 to Hirose et al .; No. 5,989,426; 5,843,351; 5,843,351; 5,733,602; 5,614,099; And 5,576,057 disclose an aqueous amine solution prior to interfacial polymerization of selected alcohols, ethers, ketones, esters, halogenated hydrocarbons, nitrogen-containing compounds and sulfur-containing compounds having a solubility parameter of 8 to 14 (cal / cm ³ ) ^1/2 . And / or to an aqueous organic acid halide solution.

Methods of improving membrane performance by post-treatment are also known. For example, US Pat. No. 5,876,602 to Jones et al. Describes treating polyamide composite membranes with aqueous chlorination agents to improve membrane stability against flow, low salt passage, and / or base. US Pat. No. 5,755,964 to Mickols describes a process for treating a polyamide partition layer with ammonia or selected amines such as butylamine, cyclohexylamine and 1,6 hexane diamine. US Pat. No. 4,765,897 to Cadotte describes treating the membrane with a strong inorganic acid followed by a removal enhancer.

The gist of the invention

Aspects of the present invention provide a multilayer membrane comprising a modified separator layer that can provide improved removal rates compared to a membrane having an unmodified separator layer. Aspects of the present invention also include methods of making such membranes, including methods that can be applied to manufacture of industrial scale membranes. In addition, embodiments of the present invention may be suitable for making both nanofiltration membranes and reverse osmosis membranes.

Brief description of tables and drawings

Table 1 shows the flow for membranes with modified separator layers.

Table 2 shows the sodium chloride removal rates and flows for membranes with modified separator layers.

Tables 3 and 4 show the flow for membranes with increased modified compound concentrations.

Tables 5 and 6 show Electron Scanning Chemical Analysis (ESCA) for membranes with modified separator layers.

Table 7 shows the flow and passage rates of sodium chloride, isopropyl alcohol and nitrate for membranes with modified separator layers.

Table 8 shows the flow and passage rates of sodium chloride, isopropyl alcohol and nitrate for membranes with modified separator layers.

Table 9 shows the flow and passage rates of sodium chloride, isopropyl alcohol and nitrate for membranes with modified separator layers.

Table 10 shows the flow and passage rates of sodium chloride, borate isopropyl alcohol and nitrate for membranes with modified separator layers.

Table 11 shows the passage rates of isopropyl alcohol, borate and nitrate for membranes with modified separator layers.

Table 12 shows the flow and sodium chloride passage rates for membranes with modified separator layers.

Table 13 shows the names, types and modifying compounds of the membranes.

Table 14 shows the distribution of membranes in a rotating disk reactor system.

Table 15 shows the names of the membrane assay types for each membrane.

Table 16 shows the average increase in biofilm for each membrane.

1 shows the passage of sodium chloride, isopropyl alcohol and nitrate for a membrane with a modified separator layer.

2 shows the cryo-sectioning analysis results for each membrane.

Aspects of the present invention include multilayer membranes having modified separator layers and methods for making the same. Embodiments of the present invention also include membranes with modified separator layers having improved removal rates. In addition, embodiments of the present invention include a membrane having a modified separator layer having improved antibacterial properties. Embodiments of the present invention show an improvement over membranes with unmodified partition layers.

The membranes of the present invention may comprise a modified separator layer, wherein the separator layer is modified by applying the modifying composition to the separator layer. The modifying composition is disposed over at least a portion of the surface of the separator layer to form a modified composition layer fixed to the separator layer by one or more of hydrogen bonds, ionic bonds, covalent bonds, physical entanglements, and chemical bonds. As used herein, "physical entanglement" refers to polymers such as long chain molecules, such as phenyl amines intertwined with one another, or, for example, polyamides contained in a polyamide separator layer instead of chemically bonding to the separator layer. The process of having a long chain is said. In some embodiments, the chemical bond may be one or more of amines including amides, sulfamides, urethanes, ureas, thioesters, and secondary amines, tertiary amines, quaternary amines, and beta hydroxyl amines.

In some embodiments, the membranes of the present invention can be prepared by post-treatment on already formed separator layers such as composite polyamide reverse osmosis membranes (eg, "FT-30 ™" available from FilmTec Corporation). Can be. In some embodiments, the post-treatment can be performed by adding various compounds to the aqueous solution and coating the aqueous solution on the already formed separator layer. In addition, process steps may be performed as discussed herein later. In various embodiments, the modification can be accomplished during membrane fabrication (eg, immediately after initiation of interfacial polymerization of the polyamine and polyfunctional acid halide reactions, as discussed herein). In embodiments where the modifying composition is not soluble in aqueous solution, the modifying can be accomplished during membrane fabrication by adding various compounds to the aqueous solution. As the aqueous solution passes through the membrane, various compounds may be present at higher concentrations on the surface of the separation layer and may be immobilized to the separation layer by hydrogen bonds, ionic bonds, covalent bonds, physical entanglements, and / or by forming chemical bonds. . In some embodiments, the type and / or degree of immobilization may depend on the molecular weight and chemical composition of the various compounds applied to the separation layer, and / or the molecular weight and chemical composition of the reaction product formed from the mixing of the various compounds. As discussed herein, the presence of various compounds used to modify the surface of the separator layer is characterized by a fouling resistant surface, an improved salt removal rate, an improved solute compared to a membrane having an unmodified separator layer. It is possible to provide a membrane with one or more improvements, including removal rates, improved small organics removal rates, and / or improved antibacterial properties. As used herein, "rejection" refers to the percentage of solute concentration removed from the system feed water by the membrane.

The membranes of the present invention can be prepared by applying an aqueous coating composition to at least a portion of the surface of a porous substrate to form a first coated substrate. The aqueous coating composition may comprise one or more polyfunctional compounds selected from polyfunctional amines, polyfunctional alcohols, polyfunctional thiols, and polyfunctional anhydrides.

In some embodiments, the concentration of the multifunctional compound in the aqueous coating composition may range from about 0.1 to 10 weight percent, and preferably from about 0.5 to 7.0 weight percent, based on the weight of the total aqueous coating composition. In addition, the coating may be accomplished by spraying, membrane coating, rolling or using a dip tank, among other coating techniques. Excess solution may be removed from the support by air and / or a hand knife, dryer or oven, among others.

The separation layer can then be formed on at least a portion of the surface of the porous substrate by applying the organic solvent composition to the first coated substrate. The organic solvent composition may comprise one or more of an organic solvent and a polyfunctional acid halide, polyfunctional anhydride and polyfunctional dianhydride. The polyfunctional acid halide is dissolved in the non-polar organic solvent in the range of about 0.01 to 5% by weight, preferably 0.02 to 2% by weight, based on the weight of the total non-polar organic solvent, May be delivered in part.

The separation layer formed from the interfacial polymerization of the aqueous coating composition and the organic solvent composition may, as further discussed herein, react product of the multifunctional compound with one or more of the polyfunctional acid halide, polyfunctional anhydride and polyfunctional dianhydride. It may include.

In some embodiments, the separator layer can be a polyamide separator layer. Polyamide partition layers may be prepared by interfacial polymerization of a multifunctional compound (eg, a polyfunctional amine monomer) with a polyfunctional acid halide, wherein each term is a single species or multiple on one or more surfaces of the porous support. It is intended to refer to both the use of a combination of amines of species or the use of a combination of acid halides. As used herein, “polyamide” is a polymer in which amide bonds (—C (O) NH—) occur along the molecular chain.

As discussed herein, the polyfunctional amine monomer and polyfunctional acid halide can be delivered to the porous support in a coating step with a solution, where the polyfunctional amine monomer is coated with an aqueous solution and the polyfunctional acid halide is with an organic solvent. Can be coated. Although the coating step may be “non-sequential” (eg, not in a particular order), the polyfunctional amine monomer is preferably first coated on the porous support, followed by the polyfunctional acid halide.

The polyfunctional amine monomers used in the present invention to form the polyamide partition layer may have primary or secondary amino groups and may be aromatic (eg m-phenylenediamine, p-phenylenediamine, 1, 3,5-triaminobenzene, 1,3,4-triaminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,4-diaminoanisole and xylylenediamine) or aliphatic ( Ethylenediamine, propylenediamine and tris (2-diaminoethyl) amine). Examples of preferred polyfunctional amine monomers are primary amines having two or three amino groups, for example m-phenylene diamine (MPD), and secondary aliphatic amines having two amino groups, for example Piperazine. As discussed herein, the multifunctional amine monomer may be applied to the porous support as an aqueous coating composition. Once coated on the porous support, excess aqueous coating composition may optionally be removed.

As discussed herein, the polyfunctional acid halide can be delivered in the vapor phase (eg, in the case of a polyfunctional acid halide with sufficient vapor pressure), but the polyfunctional acid halide is preferably covered with an organic solvent. The polyfunctional acid halide is not particularly limited, and aromatic or alicyclic polyfunctional acid halides can be used. Non-limiting examples of aromatic polyfunctional acid halides include trimesic acid chloride, terephthalic acid chloride, isophthalic acid chloride, biphenyl dicarboxylic acid chloride, and naphthalene dicarboxylic acid dichloride. Non-limiting examples of cycloaliphatic polyfunctional acid halides include cyclopropane tricarboxylic acid chloride, cyclobutane tetracarboxylic acid chloride, cyclopentane tricarboxylic acid chloride, cyclopentane tetracarboxylic acid chloride, cyclohexane tricarboxylic acid chloride, tetrahydrofuran tetracarboxylic acid chloride, cyclo Pentane dicarboxylic acid chloride, cyclobutane dicarboxylic acid chloride, cyclohexane dicarboxylic acid chloride and tetrahydrofuran dicarboxylic acid chloride. One preferred polyfunctional acid halide is trimesoyl chloride (TMC).

Suitable organic solvents are those which can dissolve polyfunctional acid halides and cannot be mixed with water. Preferred solvents include those that are safe enough to carry out conventional processes without extreme precautions in terms of their flash point and film flammability without destroying the ozone layer. High boiling hydrocarbons, ie those having a boiling point above about 90 ° C., such as hydrocarbons having 8 to 14 carbon atoms, and mixtures thereof, have better flash points than hydrocarbons having 5 to 7 carbon atoms, but they are less volatile. For example, useful organic solvents include hydrocarbons such as n-hexane or cyclohexane, high purity isoparaffinic materials such as Isopar ^™ (Exxon), or Freon ^™ [including trifluorotrichloroethane] : This. children. Halogenated hydrocarbons such as DuPont Co.].

Upon contact with each other, the polyfunctional acid halides and polyfunctional amine monomers react at their surface interface to form a polyamide partition layer.

The reaction time of the polyfunctional acid halide and the polyfunctional amine monomer may be less than 1 second, but the contact time is in the range of 1 to 6 seconds, after which the excess liquid may be optionally removed by air knife, water bath (s), dryer or the like. have. Removal of excess water and / or organic solvent can be accomplished by drying at elevated temperature, eg, about 40 ° C. to about 120 ° C., although air drying at ambient temperature may be used.

Aspects of the present invention include a method of modifying a separator layer prepared as discussed herein by applying the modifying composition to at least a portion of the surface of the separator layer to form a modified separator layer. The modifying composition can include an organic solvent, as further discussed herein, and a reactive modifying compound comprising a functional group.

As discussed herein, the separator layer may comprise residual reactive moieties of the multifunctional compound and one or more reaction products of the polyfunctional acid halide, polyfunctional anhydride, and polyfunctional dianhydride. The residual reactive moiety can be one or more of an unreacted functional group on a polyfunctional compound, an unreacted functional group on a polyfunctional acid halide, an unreacted functional group on a polyfunctional anhydride, and an unreacted functional group on a polyfunctional dianhydride. have. The residual reactive moiety can also be a hydrolysis product of a polyfunctional compound, a hydrolysis product of a polyfunctional acid halide, a hydrolysis product of a polyfunctional anhydride and / or a hydrolysis product of a polyfunctional dianhydride.

Preferably, the modifying composition may be applied after interfacial polymerization to form the separator layer, but before the step of limiting or removing residual-reactive moieties on the separator layer, such as washing or drying. In addition, by applying the modifying composition at this point in the process, slight changes in the existing film making process may be required. However, embodiments include applying the modified composition to the separation layer at a particular time of the process after applying the organic solvent composition containing the polyfunctional acid halide as discussed herein. The process of the invention only requires that a sufficient number of residual reactive moieties be available in the separation layer. In some embodiments, an appropriate number of residual reactive moieties will depend on the desired change.

In order to modify the separator layer, embodiments of the present invention utilize the residual reactive moieties on the separator layer remaining after the interfacial polymerization reaction step, as discussed herein. In some embodiments, useful residual reactive moieties on the separator layer may depend on the starting material for interfacial polymerization. For example, in embodiments where the polyfunctional amine monomer is meta-phenylene diamine (MPD) and the polyfunctional acid halide is trimesic acid chloride (TMC), the reactive moiety on the dividing layer may be a polyfunctional amine and a polyfunctional acid chloride. Derivatives may be included. Thus, the separation layer may comprise two sites (eg Y and Z) for the added group shown in formula (I):

Separately, polyfunctional amines can be represented by Formula (II); Carboxylic acids present as reactive moieties on the partition layer, resulting from hydrolysis of polyfunctional acid chlorides, can be represented by compounds of Formula III:

As discussed herein, a method of making a membrane includes forming a modified separator layer by applying the modifying composition to at least a portion of the surface of the separator layer. In some embodiments, the modifying composition can include a reactive modifying compound that includes an organic solvent and a functional group. In some embodiments, the organic solvent of the modifying composition may be the same solvent used for the polyfunctional acid halide, as discussed herein.

In previous attempts to improve the removal rate of existing membranes, modification of the membranes generally included adding the modifier to the aqueous phase during or after the washing or hydrolysis step. Thus, modifiers have been limited to water soluble polymers and chemicals and have limited the choice of functional groups that can be used with the membrane. However, embodiments of the present invention include reactive modifying compounds that are soluble or at least dispersible in an organic solvent. The use of organic solvents allows a wide selection of reactive modifying compounds to be used to dissolve high molecular weight reactive modifying compounds such as aromatics and aliphatic having 5 or more carbon atoms. In addition, because the organic solvent is poorly soluble in water, organic soluble reactive modifying compounds may not be removed and / or washed while using the obtained multilayer membrane in a water purification process.

In addition, one aspect of an aspect of the present invention is to select reactive modifying compounds that change the selectivity properties of the separation layer without significantly reducing the flow through the membrane below industrial requirements. The reactive modified compound may be selected from substituted or unsubstituted aromatic compounds, alicyclic compounds, pyridine or five or more linear aliphatic compounds.

In embodiments in which the reactive modifying compound comprises a functional group that reacts with the separating layer, thereby fixing the modifying composition to the separating layer via chemical bonding, the reactive modifying compound, together with the remaining reactive moieties on the separating layer, may be combined with amines, amides, sulfamides, Functional groups capable of forming urethanes, ureas, thioesters, aminoesters, esteramides, imides, secondary amines, tertiary amines, quaternary amines, or beta hydroxyl amine bonds. Preferred reactive modifying compounds can be selected from aniline derivatives and straight or cyclic amines having 5 or more carbon atoms.

In some embodiments, there is a tight bond between the amide, isocyanate, urethane, urea, sulfamide, thioester, aminoester, esteramide, imide, secondary amine, tertiary amine, quaternary amine or beta hydroxyl amine and functional group. It is desirable to select reactive modifying compounds that can provide a bond. This may allow for better removal rates and selectivity.

As discussed herein, the reactive modifying compound may comprise a functional group. The functional group can be selected from the group consisting of amines, aminoalcohols, aminoesters, esters, thioesters, ethers, alcohols, anhydrides, epoxides, acid halides, isocyanates, 2-oxazolines, thiols, thiophenols, disulfides and azides Can be. In addition, as discussed herein, in some embodiments, functional groups may react with residual reactive moieties on a separator layer to form chemical bonds.

In embodiments in which the functional group reacts with the residual reactive moiety on the separation layer to form a chemical bond, the modified compound may include a functional group selected based on the residual reactive moiety to which the functional group reacts best. For example, as discussed herein, the residual reactive moiety can be the amine of the polyamide partition layer. Possible functional groups that can effectively react with such amines may include acid halides, epoxides, isocyanates, diisocyanates and azide. For example, aliphatic epoxy modified compounds can react with residual amine residues to form beta hydroxyl amines. Similarly, aliphatic isocyanate modified compounds can react with residual amine residues to form substituted ureas, and diisocyanate modified compounds can react with residual amine residues to form urethanes.

In some embodiments, the remaining reactive moiety can be an acid halide and / or carboxylic acid of the polyamide separator layer. In such embodiments, amines, 2-oxazolines and alcohols are present in the available basic and / or nucleophilic, organic soluble compounds that can be selected as functional groups on the modifying compound. In various embodiments, aromatic structures are preferred because they are stable enough to handle without serious health and safety concerns. In addition, larger modified compounds can produce more significant changes in selectivity properties, compared to similar modified compounds, in modified partition layers, and thus in membranes.

An example of a modified compound that reacts with residual acid halide residues and / or residual carboxylic acid residues is aniline. The amines on aniline can react with unreacted acid chlorides and / or carboxylic acids on the separator layer. Other suitable reactive modifying compounds for reacting with acid halides and / or carboxylic acids include, but are not limited to, aliphatic secondary amines, aromatic amines, tertiary amines, and amides.

Other embodiments include modified compounds having a functional group selected from the group comprising esters, thioesters, ethers, alcohols, anhydrides, 2-oxazolines, thiols, thiophenols, and disulfides. The reactive modifying compound can then be chosen in particular from aliphatic amines, aromatic amines, azides, isocyanates, esters, anhydrides, epoxides, 2-oxazolines, amides, tresylates, tosylates, and mesylates.

In some embodiments, the reactive modifying compound can include a functional group as discussed herein, and a pendant functional group. In some embodiments, pendant functional groups can be selected to change one or more properties of the separator layer. For example, the pendant functional group can be an organic metallic material that can provide a partition layer with antibacterial properties. In some embodiments, the reactive modifying compound can include functional groups that can react with reactive residues remaining on the separator layer to produce chemical bonds and pendant functional groups that can change the properties of the separator layer.

In some embodiments, the reactive modifying compound may comprise one pendant functional group. However, embodiments also include reactive modifying compounds having a plurality of pendant functional groups. In addition, the reactive modified compound may comprise multiple pendant functional groups of the same compound and / or multiple pendant groups present in different compounds.

In some embodiments, the reactive modified compound is an alkyl group, alkene group, alkyne group, aliphatic amine (including primary, secondary or tertiary amine), aromatic amine, ester, ketone, aldehyde, thioester, amide, sulfamide Selected from alcohols, ethers, isocyanates, thiols, sulfides, disulfides, sulfates, sulfites, thiophenols, thiophenes, halogens, silyls, silicon-containing organometallic compounds, phosphorus-containing organometallic compounds, other organometallic compounds, and metal complexes Pendant functional groups. The pendant functional group may also be selected from organometallic derivatives of aliphatic amines, aromatic amines, amides, sulfamides, ureas, esters, ethers, acids, alcohols and urethanes. In embodiments where the reactive modifying compound is an aliphatic or aromatic thiol, the pendant functional group (s) can be metal ions. In addition, in embodiments where the reactive modifying compound is an aliphatic having 5 or more carbons, the pendant functional group may be a quaternary amine, which is a biocidal group and can impart bactericidal properties to the resulting membrane.

In embodiments in which the functional group is an amine, the reactive modifying compound may be phenyl amine and the pendant functional group may be a halide, ether, ester, ketone, aldehyde, alcohol, thiol, methiol, amine, phosphorus, metal complex, and organic It can be selected from metallic compounds. Formula IV represents a possible candidate position of the pendant functional group, where the reactive modifying compound is phenyl and the functional group is an amine.

In Formula IV,

A, B, C, D and E represent various positions that can be occupied by pendant functional groups on the aromatic ring. As discussed herein, one or more pendant functional groups may be attached to a ring, and each pendant functional group may be the same or different. In some embodiments, two and / or three of the same pendant functional groups can be attached to the ring to more effectively change the properties of the partition layer compared to using one pendant functional group attached to the ring. have. As discussed herein, pendant functional groups may also be attached to aliphatic reactive modifying compounds.

In embodiments in which the reactive modifying compound is phenyl amine, a non-IUPAC name identifying the pendant functional group obtained can be used. For example, m-phenetidine is named 3-ethoxyaniline or m-ethoxyaniline, which leaves an ethoxy pendant functional group. Similarly, 3-aminothiophenol can be named 3-thioaniline and the pendant functional group obtained is thiol. Finally, if MPD is used, it will be named 3-aminoaniline and the pendant functional group can be an amine.

In some embodiments, the reactive modifying compound can be phenyl amine and the pendant functional group can be selected from halides and thiols. Such embodiments include, but are not limited to, 2 chloro aniline, 3 chloro aniline, 4 chloro aniline, 2,3 dichloro aniline, 2,4 dichloro aniline, 2,5 dichloro aniline, 3,4 dichloro aniline, 3,5 dichloro Aniline, 2,6 dichloro aniline, 2,3,4 trichloro aniline, 3,4,5 trichloro aniline, 2,4,5 trichloro aniline, 2,4,6 trichloro aniline, 3,4,5, 6 Tetrachloro Aniline, 2,4,5,6 Tetrachloro Aniline, 2,3,5,6 Tetrachloro Aniline, 2,3,4,5,6 Pentachloro Aniline, 2 Bromoaniline, 3 Bro Mononiline, 4 bromo aniline, 2,3 dibromo aniline, 2,4 dibromo aniline, 2,5 dibromo aniline, 2,6 dibromo aniline, 3,4 dibromo aniline, 3, 5 dibromo aniline, 2,3,4 tribromo aniline, 3,4,5 tribromo aniline, 2,4,5 tribromo aniline, 2,4,6 tribromo aniline, 3,4, 5,6 tetrabromoaniline, 2,4,5,6 tetra Lomoaniline, 2,3,5,6 tetrabromoaniline, 2,3,4,5,6 pentabromoaniline, difluoroaniline, trifluoroaniline, tetrafluoroaniline, 2,3 difluoro Aniline, 2,4 difluoro aniline, 2,5 difluoro aniline, 2,6 difluoro aniline, 3,4 difluoro aniline, 3,5 difluoro aniline, 2,3,4 trifluoro Aniline, 3,4,5 trifluoro aniline, 2,4,5 trifluoro aniline, 2,4,6 trifluoro aniline, 3,4,5,6 tetrafluoro aniline, 2,4,5, 6 tetrafluo aniline, 2,3,5,6 tetrafluoro aniline, 2,3,4,5,6 pentafluoro aniline, 2 iodo aniline, 3 iodo aniline, 4 iodo aniline, 2,3 Diiodo aniline, 2,4 diiodo aniline, 2,5 diiodo aniline, 2,6 diiodo aniline, 3,4 diiodo aniline, 3,5 diiodo aniline, 2,3,4 Triiodoaniline, 3,4,5 triiodoaniline, 2,4,5 triiodoline , 2,4,6 triiodoaniline, 3,4,5,6 tetraiodoaniline, 2,4,5,6 tetraiodoaniline, 2,3,5,6 tetraiodoaniline, 2,3 , 4,5,6 pentaiodoaniline, 2 methoxy aniline, 3 methoxy aniline, 4 methoxy aniline, 2,3 dimethoxy aniline, 2,4 dimethoxy aniline, 2,5 dimethoxy aniline, 2,6 Dimethoxy aniline, 3,4 dimethoxy aniline, 3,5 dimethoxy aniline, 2,3,4 trimethoxy aniline, 3,4,5 trimethoxy aniline, 2,4,5 trimethoxy aniline, 2, 4,6 trimethoxy aniline, 2,3,4,5 tetramethoxy aniline, 2,3,4,5,6 pentamethoxy aniline, 2 ethoxy aniline, 3 ethoxy aniline, 4 ethoxy aniline, 2 , 3 diethoxy aniline, 2,4 diethoxy aniline, 2,5 diethoxy aniline, 2,6 diethoxy aniline, 3,4 diethoxy aniline, 3,5 diethoxy aniline, 2,3,4 triethoxy aniline , 3,4,5 triethoxy aniline, 2,4,5 triethoxy aniline, 2,4,6 triethoxy aniline, 2 propoxy aniline, 3 propoxy aniline, 4 propoxy aniline, 2,3 dipropoxy aniline, 2,4 dipropoxy aniline, 2,5 dipropoxy aniline, 2,6 dipropoxy aniline, 3,4 Dipropoxy aniline, 3,5 dipropoxy aniline, 2,3,4 tripropoxy aniline, 3,4,5 tripropoxy aniline, 2,4,5 tripropoxy aniline, 2,4,6 tripro Foxy Aniline, 2 Butoxy Aniline, 3 Butoxy Aniline, 4 Butoxy Aniline, 2,3 Dibutoxy Aniline, 3,4 Dibutoxy Aniline, 3,5 Dibutoxy Aniline, 2,3,4 Tributoxy Aniline, 3 , 4,5 tributoxy aniline, 2 hydrothio aniline, 3 hydrothio aniline, 4 hydrothio aniline, 2,3 dihydrothio aniline, 2,4 dihydrothio aniline, 2,5 dihydrothio aniline, 2, 6 dihydrothio aniline, 3,4 dihydrothio aniline, 3,5 dihydrothio aniline, 2 methylthio aniline, 3 methylthio aniline, 4 Methylthio aniline, 2-acetyl aniline, 3-acetyl aniline, 4-acetyl aniline, 2,3 diacetyl aniline, 3,4 diacetyl aniline, 3,5 diacetyl aniline, 2-carbmethoxy aniline, 3-carbmethoxy aniline, 4 Carbmethoxy Aniline, 2 Carethoxy Aniline, 3 Carethoxy Aniline, 4 Cabethoxy Aniline, 3 Hydroxy Aniline, 4 Hydroxy Aniline, 2 Carbmethoxy-4-bromoaniline, 2 Carbmethoxy-5 -Bromoaniline, 2-carbmethoxy-6-bromoaniline, 2-carbmethoxy-3-bromoaniline, 2-carbmethoxy-4-chloroaniline, 2-carbmethoxy-5-chloroaniline, 2-carbme Oxy-6-chloroaniline, 2 carbmethoxy-3-chloroaniline, 2 carethoxy-4-bromoaniline, 2 carethoxy-5-bromoaniline, 2 carethoxy-6-bromoaniline, 2 carethoxy-3-bromoaniline, 2 carethoxy-4-chloroaniline, 2 carethoxy-5-chloroaniline, 2 carethoxy-6-chloro Aniline, 2 carethoxy-3-chloroaniline, 2 acetyl-4-bromoaniline, 2 acetyl-5-bromoaniline, 2 acetyl-6-bromoaniline, 2 acetyl-3-bromoaniline, 2 acetyl -4-chloroaniline, 2 acetyl-5-chloroaniline, 2 acetyl-6-chloroaniline, 2 acetyl-3-chloroaniline, 2 methoxy-4-bromoaniline, 2 methoxy-5-bromoaniline, 2 methoxy-6-bromoaniline, 2 methoxy-3-bromoaniline, 2 methoxy-4-chloroaniline, 2 methoxy-5-chloroaniline, 2 methoxy-6-chloroaniline, 2 methoxy 3-chloroaniline, mixed halogenated aniline, for example 2-halo aniline, 3-halo aniline, 4-halo aniline, 2,3 diahalo aniline, 2,4 diahalo aniline, 2,5 dia Halo aniline, 2,6 diahalo aniline, 3,4 diahalo aniline, 3,5 diahalo aniline, 2,3,4 trihalo aniline, 3,4,5 trihalo aniline, 2, 4,5 trihalo aniline, 2,4,6 trihalo aniline, 3,4,5,6 Trahalo aniline, 2,4,5,6 tetrahalo aniline, 2,3,5,6 tetrahalo aniline, and 2,3,4,5,6 pentahalo aniline, N, N-ethyl ethyl Amine, N, N-ethanol ethyl amine, diethanol amine, N, N propyl propyl amine, N, N propyl propanol amine, dipropanol amine, N, N butyl butyl amine, N, N butyl butanolamine, dipropanol amine, Dimethyl amine, diethyl amine, dipropyl amine, and dibutyl amine.

In some embodiments in which the functional group is an amine, the reactive modifying compound can include pendant functional groups as discussed herein, non-limiting examples of such reactive compounds include:

In some embodiments, the modified composition containing the organic solvent and the reactive modifying compound can be a dehydrating composition, wherein the modifying composition is separated layer using a condensation reagent such as N, N'-dicyclohexylcarbodiimide (DCC). Drain the water from the In various embodiments, by draining water from the separation layer, unreacted functional groups on the multifunctional compound react with the hydrolysis products of the polyfunctional acid halides (e.g., carboxylic acids) to form amide bonds, ester bonds or ether bonds. can do.

Those skilled in the art can appreciate that the method embodiments of the present invention can be modified to include other steps. Coating processes such as the use of surfactants or other humectants to coat the porous support layer, post-treatment of the membrane, cleaning of the membrane with water, and the like can also be used in aspects of the present invention.

In addition, as discussed herein, the membrane may comprise a porous support. The porous support can be a microporous support. In various embodiments, the microporous support may be a polymeric material having a pore size such that the permeate passes but is not too large to prevent bridging over the polyamide thin film formed thereon. For example, the pore size of the support can range from 1 nm to 500 nm. Pore diameters greater than 500 nm may in some cases disrupt the flat sheet morphology required in some embodiments by allowing the polyamide film to be sagging into the pores. Examples of porous supports include polysulfones, polyether sulfones, polyimides, polyamides, polyetherimides, polyacrylonitriles, poly (methyl methacrylates), polyethylene, polypropylene and various halogenated polymers such as polyvinyl Include those made of lidene fluoride. Porous supports can also be made of other materials. In some embodiments, the porous support may have a thickness in the range of 25 μm to 125 μm. As used herein, “permeate” refers to purified water produced by the membrane system.

Aspects of the present invention also include multilayer films. In some cases, the multilayer film can be prepared according to the methods described herein. The multilayer membrane may comprise a porous substrate having a modified separator layer comprising an inner side and an outer side and a first side parallel to the second side, wherein the inner side is operatively associated with one or more sides of the porous substrate. In contact. The portion of the modified separator layer disposed between the inner side and the outer side and the outer side comprise a plurality of pendant functional groups. The pendant functional group can be linked to the partition layer modified by one or more hydrogen bonds, ionic bonds, covalent bonds, physical entanglements and chemical bonds, where the chemical bonds are one or more amides, sulfamides, urethanes, ureas, thioesters And amines such as secondary amines, tertiary amines, quaternary amines and beta hydroxyl amines.

As discussed herein, in embodiments in which the pendant functional group is linked to the separation layer modified by chemical bonding, the reactive modifying compound is linked to the separation layer by reaction of the functional group with residual reactive moieties on the separation layer. Can be. Thus, the pendant functional group on the modified separator layer corresponds to the pendant functional group attached to the reactive modifying compound as discussed herein.

In some embodiments, pendant functional groups can be characterized as residues that change the properties of the separation layer as compared to the unmodified separation layer. For example, pendant functional groups can change the selectivity properties of the separation layer for solute molecules.

In some embodiments, pendant functional groups are linked to the modified separator layer by covalent bonds to the separator layer, making the pendant functional group difficult for the multilayer membrane to be removed by washing. In addition, the pendant functional groups may form a thin layer on top of the modified separator layer. By forming a thin layer of pendant functional groups on top of the modified separator layer (ie, the outer face), the pendant functional groups are present in small amounts as compared to how the pendant functional groups are dispersed throughout the separator layer. Can be. Thus, a thin layer of pendant functional groups on the surface can reduce the flow loss in embodiments in which the selected pendant functional group is known to cause flow loss.

In some embodiments, although not useful for preparing the membrane alone, in certain cases, certain pendant functional groups can be selected that can be used to impart properties that are not available for the membrane. For example, biocidal groups and metal-binding sites can be added. In a further embodiment, a pendant functional group can be selected that is a binding group, where the pendant functional group can be used to attach another polymer to the modified separator layer surface.

Secondary Ion Mass Spectroscopy (SIMS), Electron Scanning Chemical Analysis (ESCA), X-ray Microscopy, Energy Dispersive X-ray Analysis (EDX), and Scanning Transmission Electron Microscopy (TEM /) Surface analysis techniques such as EEL) can indicate the percentage of pendant functional groups in the separating layer.

In addition, SIMS analysis can be used to demonstrate that the pendant functional groups are more or less concentrated to some extent near the surface of the separation layer, but are also linked to the separation layer through chemical bonding. Depending on the size and chemistry of the reactive modifying compound, pendant functional groups are present at slightly higher concentrations in the upper half (1/2) of the depth of the separation layer and can be found throughout the separation layer, creating a multilayer film. . This is in contrast to other methods of modifying the separation layer, such as direct chlorination of the polyamide separation layer, in which chlorine groups remain attached to the separation layer throughout all parts of the separation layer.

As discussed herein, surface analysis techniques can be used to indicate the percentage of pendant functional groups in the separating layer. In some embodiments, ESCA can be used to quantify atomic surface percentages. For example, for modified MPD-TMC membranes, the percentage of pendant functional groups to MPD derived groups on the surface of the separation layer can be assessed. In some embodiments, aniline in combination with halogen and thiol can be readily quantified by ESCA using the reactive modifying compound.

In such membranes, the atomic percentage of nitrogen and thus the total number of amines on the separator layer surface prior to application of the modifying composition is only due to the MPD. However, after applying the modifying composition, the atomic percentage of nitrogen results from both MPD and aniline in the reactive modifying compound. To calculate the total surface percentage of nitrogen, two considerations are important; The first is that the MPD derived moiety contains two nitrogens, and the second is that the penetration depth of the ESCA should be on average large enough to incorporate both nitrogen on the MPD. Using these considerations, total nitrogen in terms of MPD and aniline can be described as shown in Equation 1:

Total surface nitrogen percentage (% TSN) = N from MPD + N from aniline

                        = 2 x surface MPD + aniline

Subsequently, when the thiol or halogen is derived from pendant functional groups on aniline, the atomic percentage of sulfur or halogen is a direct measure of surface application of aniline. As used herein, the atomic percentage of mono-thiol or mono-halogenated aniline can be expressed as atomic percentage X%. In embodiments in which aniline contains a plurality of pendant functional groups, the atomic percentage (X%) can be divided by the average number of pendant functional groups per reactive modified compound. For mono-pendant functional group aniline, surface application can be evaluated using Equation 2:

The attempt described above is used in the Examples section below to evaluate the surface application for 3-thioaniline and 3-chloroaniline on a membrane with an MPD-TMC partition layer. For example, in some embodiments, the pendant functional group constitutes about 10 to 45% of the modified separator layer, calculated as a percentage of added pendant functional group to the chemical group of the separator layer, as discussed herein. do. In addition, in some embodiments, the modified separator layer has a ratio of residues derived from pendant functional groups in the region near the outer face of the modified separator layer, relative to the region near the inner face of the separator layer, about 1.5: 1 days. Can be.

In some embodiments, the multilayer film can have a modified surface charge compared to a film with an unmodified partition layer. Reduction of surface charge can reduce organic contamination of the film and can also produce other effects. For example, polyamide membranes prepared by interfacial polymerization of MPD and TMC can have two surface-bonded modified species due to residual amines and acids. Some operating conditions for making the polyamide separator layer may produce an MPD-TMC separator layer with a surface negative charge due to residual acid groups. However, in embodiments of the invention, the multilayer membrane reacts with functional groups on the reactive modifying compound, as discussed herein, or when the carboxylic acid groups are discussed herein, N, N'-dicyclohexylcarbodiimide ( Additional condensation reagents such as DCC) may react with the MPD and thus have a nearly neutral charge.

Another important property of the film is the surface energy of the film. Since surface energy is the main effect of regulating the flow through the membrane, the surface energy of the membrane can be measured to determine if the pendant functional group can cause a change in flow compared to a similar membrane without this functional group. .

By measuring how the surface energy changes when the pendant functional group changes, the insolubility of the pendant functional group on the reactive modifying compound can be determined. In some embodiments, the degree of improvement in flow by pendant functional groups on the aniline reactive modifying compound can be measured. In some embodiments, ketones may be nearly identical to multiple methyl ethers and thiols, ketones may be more useful than single methyl ethers, single methyl ethers may be more useful than esters, and esters are more useful than methiol And methol may be more useful than primary amines, primary amines may be more useful than secondary amines, and secondary amines may be more useful than tertiary amines. Or ketone-many methyl ether-thiol> single methyl ether> ester> methiol> primary amine> secondary amine> tertiary amine. In addition, in some embodiments, multiple pendant functional groups on a single reactive modifying compound can increase the flow improving effect.

In some embodiments, where the pendant functional group on the modified separator layer is selected from ethers, ketones, and thiols, the multilayer membrane comprising the modified separator layer is more than one nitrate, silica compared to the membrane without the modified separator layer. The removal rate of solutes, including boric acid, arsenic, and selenium and metal salts can be improved. In addition, multilayer membranes can increase the removal rate of small organics, including one or more alcohols, disinfection by-products, halogenated solvents, drugs, and endocrine disruptors. As used herein, "disinfection by-products" refers to by-products formed when the fungicides used in a water treatment plant react with bromide and / or natural organics (eg, decaying plants) present in feed water. Different bactericides produce different types or amounts of disinfection byproducts. Disinfection by-products may include, but are not limited to, trihalomethane, haloacetic acid, bromate and chlorite. In addition, halogenated solvents include methylene chloride (dichloromethane), methyl chloroform (1,1,1-trichloroethane), perchloroethylene (tetrachloroethylene) and trichloroethylene, and pharmaceuticals are particularly antibiotics, anti-depressants , Birth control pills, seizure medications, chemotherapy drugs, antibiotics, hormones, analgesics, ibuprofen, aspirin, sedatives, cholesterol-lowering compounds and caffeine. Also, as used herein, an "endocrine disruptor" is a synthetic compound that, when absorbed into the body, mimics or blocks hormones and destroys the normal functioning of the body. Such destruction can occur by altering normal hormone levels, stopping or stimulating hormone production, or by affecting the functions these hormones regulate by altering the way hormones pass through the body. Endocrine disruptors may include diethylstilbestol, dioxin, polychlorinated biphenyls (PCB), dichloro-diphenyl-trichloroethane (DDT), and some other pesticides.

As discussed herein, in some embodiments, the chemical bonds in the modified separator layer may be more robust by using certain reactive modifying compounds. For example, the chemical bond between the separation layer and the amide functional group on the aromatic reactive modifying compound may be stronger than the chemical bond between the separation layer and the amide functional group on the aliphatic reactive modifying compound. In some embodiments, tighter chemical bonds can produce higher flowable multilayer membranes as compared to multilayer membranes having less robust chemical bonds.

In some embodiments, the multilayer membrane of the present invention can be designed to reduce contamination. Membrane contamination in water systems can limit the flow through the membrane and ultimately limit the membrane's operating life. Contamination problems may include the increase of bacteria and natural materials such as natural organic matter, soap and oil in water. Contamination can also be caused by chemical or physical attraction of the membrane surface to the retentate in-plane chemicals of the membrane filtration unit. In addition, contamination due to an increase in microorganisms may be increased when additional organic material is fed to the microorganisms.

The problem of pollution has been studied in depth earlier, and although not wishing to be bound by theory, several "rules" for lower pollution have been proposed. These rules include that aromatic surfaces (eg MPD-TMC) are more contaminated compared to aliphatic surfaces (eg piperazine partition layers). Positively charged surfaces are more contaminated than negatively charged surfaces. The soft side is less contaminated than the rough side. Surfaces with biocide attached to a specific linking group length become bactericidal. Certain metal ions on the surface have been found to stop surface contamination in seawater.

However, most of these general theories are about specific foulants. Natural organic materials similar to those found in surface waters can have different pollution solutions from pollution in the oceans, bio-contamination, and contamination from synthetic contaminants such as oils and surfactants.

Aspects of the invention can be designed to reduce contamination. In some embodiments, contamination can be reduced by creating a modified separator layer surface that is physically or chemically resistant to contamination and / or by creating a bactericidal membrane for killing microorganisms. In some embodiments, the surface charge can be changed from positive to negative by adding piperazine derived pendant functional groups to the separator layer, which can soften the surface and change the surface from aromatic to mostly aliphatic. In some embodiments, the addition of bactericidal pendant functional groups can also change the surface charge.

As discussed herein, the multilayer membranes of the present invention may allow a greater range of selectivity for different chemical compounds and ions. Selectivity may depend on the pendant functional group being bonded to the modified separator layer. For example, for MPD-TMC partition layers, pendant functional groups such as 3-aminoacetophenone and 3-methoxyaniline can lead to significant improvements in the removal rates of sodium chloride, isopropyl alcohol and sodium nitrate.

Various membrane forms are commercially available and useful in the present invention. These include spirally wound forms, hollow fibers, tubular or flat sheet membranes. Regarding the composition of the membrane, the membrane often has a hygroscopic polymer other than the separator layer coated on the surface of the separator layer. Among these polymers are polymeric surfactants, polyvinyl alcohols, polyvinyl pyrrolidones and polyacrylic acids or polyhydric alcohols such as orbital and glycerin. In some embodiments, the formation of the separator layer comprises contacting the complexing agent with an organic solvent prior to the substantial reaction between the polyfunctional compound and one or more of the polyfunctional acid halide, polyfunctional anhydride, and polyfunctional dianhydride. Complexing agents can include, for example, those of the method described in US Pat. No. 6,562,266. The presence of these polymers and complexing agents generally may not affect aspects of the invention as long as the various reactive modifying compounds and the separating layer are in contact. When the separator layer is brought into contact with the final membrane form, the shape and composition of the membrane may be such that the membrane is in contact with the described modifying composition and reactive modifying compound.

As used herein, the following terms have the definition provided: “Removal rate” is the percentage of a particular substance (ie, solute) that is dissolved or dispersed that does not flow with the solvent through the membrane. The removal rate is 100 minus the percentage of dissolved or dispersed material that passes through the membrane (ie, solute passage, "salt passage" if the dissolved material is a salt). "Flow" is the rate of flow of solvent, typically water, through the membrane. A "reverse osmosis membrane" is a membrane having a removal rate of NaCl of about 95 to 100%. A "nanofiltration membrane" is a membrane having a removal rate of NaCl of about 0 to about 95% and a removal rate of one or more divalent ions or organic compounds of about 20 to about 100%.

Specific Aspects of the Invention

The following examples are provided for illustrative purposes only and are not intended to limit the scope of the invention. In addition, some of the examples provided herein include the addition of a complexing agent to improve the membrane flow obtained, as discussed herein.

Example 1

In a pilot plant membrane preparation system, a 5.2 weight / volume (wt./%) of a commercially available polysulfone support (ie, a porous substrate) was adjusted to about 10 by adding 2 mol (M) of sodium hydroxide. vol.%) in an aqueous solution of met-phenylene diamine (MPD). The support roll is pulled through the reaction table at a constant speed. Following MPD immersion, a single thin layer of 0.14 wt./vol.% Trimesoyl chloride (TMC) in high purity isoparaffin solvent (ISOPAR L, Exxon) is applied to the membrane. Excess TMC solution is removed through an air knife and suction cup. Thereafter, after the TMC / solvent layer is applied, a 10 mmol (mM) solution of the reactive modifying compound in the same solvent is applied on top of the polyamide partition layer in the monolayer thin layer. The line speed of the pilot plant machine is kept constant. Excess liquid is removed with an air knife and suction pump. The membrane is passed through a water rinse tank and a drying oven and then coated with a hygroscopic polymer.

Thereafter, the sample coupon is cut from the roll and tested.

Table 1 contains an aqueous solution containing about 32,000 parts / million parts of sodium chloride (NaCl) at a feed pH of 7 to 8 at a transmembrane pressure of 800 pounds per square inch (psi) (5,515,805.83 pascals). Data evaluating MPD-TMC partition layers modified with reactive modified compounds using test solutions is shown. Flow through the sample is allowed to run for about 30 minutes before testing.

Flow to Membrane with Modified Separation Layer Reactive Modified Compound (10 mM)  Gfd 4-isopropylaniline  9.9 Piperazine  17.6 Control  16.0

As can be seen from Table 1, the MPD-TMC partition layer loses a significant amount of flow when the reactive modifying compound is 4-isopropylaniline. However, the flow to the membrane is enhanced when the reactive modifying compound is piperazine.

Example 2

Samples of the polysulfone support are stored in water for at least 3 hours. The polysulfone support is a non-woven web made of polyethylene terephthalate (PET) coated with a polysulfone solution from dimethyl formamide (DMF) and formed by processing in water. A sample of polysulfone support is fixed to the metal frame and immersed in a 2.5 wt./vol.% Solution of MPD for at least 5 minutes. The support is placed on a paper sheet and the excess amine solution is niped off using a latex rubber roller.

Membranes 1, 2, 3 and 4 are prepared using 50 ml of a solution of TMC and ISOPAR L. The solution is prepared by adding about 49.3 ml of ISOPAR L to 0.86 mL of 5.2 wt./vol.% Raw TMC solution. The rubber barrier is placed on an MPD coated support to form a well. The TMC solution is then poured into the wells, left on the MPD-coated support for about 1 minute and then poured. The MPD-TMC-coated support is washed with hexane for about 30 seconds, air dried for about 1 minute and then placed in water. Store the sample in water until it is tested.

Membrane 5 is prepared as described above for membranes 1, 2, 3 and 4 using a solution of TMC, pyridine and ISOPAR L. The solution is prepared by adding 0.86 ml of 5.2 wt./vol.% TMC to 49.3 ml of a solution prepared from 50 ml of 50 mM pyridine in ISOPAR L.

Membrane 6 is prepared as described above for membranes 1, 2, 3, and 4 using a solution of about 50 ml of TMC and ISOPAR L. However, after about 1 minute of contact the TMC solution was drained, then 5 mM pyridine solution was added to the membrane and allowed to react for about 30 seconds. The pyridine solution is then drained and the membrane washed with hexane for about 30 seconds before the membrane is left in water.

Membrane 7 is prepared as described above for Membrane 5, but TMC, pyridine and ISOPAR L solutions are prepared by adding 25 ml of 5 mM pyridine to a solution of 0.43 ml of TMC in about 24.5 ml of ISOPAR L.

Membranes 8 and 9 are prepared as described above for membrane 5. Membrane 8 is prepared by adding 0.85 ml of TMC to 49.3 ml of a solution prepared from 12.4 ml of 5.2 mM dibutyl amine added to ISOPAR L. Membrane 9 is prepared by adding 0.85 ml of TMC to 49.3 ml of a solution prepared from 6.25 ml of 5.2 mM dibutyl amine added to ISOPAR L.

Table 2 shows data for evaluating the membrane prepared above using a test solution comprising an aqueous solution containing about 1,500 ppm NaCl at a trans membrane pressure of 150 psi (1,034,213.59 Pascals).

As can be seen from Table 2, as shown by membrane 5, pyridine can be added to the TMC solution to enhance flow to the TMC-MPD membrane, but as shown by membrane 6, after the TMC-MPD process Adding pyridine to the membrane does not have the same effect on the flow. Also, as shown by membrane 7, higher concentrations of pyridine in the TMC solution increase the flow to the TMC-MPD membrane, but are more pronounced with the use of lower concentrations of pyridine, as shown by membrane 5.

In addition, adding dibutyl amine to the TMC solution enhances sodium chloride (NaCl) removal rates, as shown by membranes 8 and 9, while membrane 9 enhances NaCl removal rates while reducing flow less than membrane 8.

Example 3

Membranes are prepared on a standard pilot coater as a continuous process at 13 feet / minute (0.066 meters / second) using a formulation for high-flow seawater membranes on a polysulfone porous substrate. First, a 3.5 wt% (wt.%) Solution of MPD is applied to a polysulfone porous substrate pre-fabricated in water. MPD application has a residence time of 156 seconds and excess MPD solution is removed using a nip roller. TMC dissolved in ISOPAR L is applied at a retention time of 132 seconds at 118 ml / ft ² . Polyamides are formed at the oil-water interface.

Thereafter, the oil is removed using an air knife and a pump. Thereafter, the modifying compound is applied. A series of runs is performed using different concentrations of 3-chloro aniline and 3-thiol aniline. Concentrations vary from 1 to 15 mM. The application rate of the modified compound is the same as that used for the TMC solution and the residence time is 180 seconds. Excess modified compound is removed with an air knife and pump. The membrane is then passed through a room temperature water bath to remove excess oil and then through a 98 ° C. bath containing 3.5% glycerin. The residence time in the soaking bath is 37 minutes. The membrane is then dried for 10.6 minutes at a temperature of 95 ° C. through an air-floatation dryer.

Tables 3 and 4 were prepared above using a test solution containing an aqueous solution comprising approximately 2,000 ppm NaCl, 5 ppm boric acid, 100 ppm isopropyl alcohol, and 100 ppm sodium nitrate at a transmembrane pressure of 125 psi (861,844.662 Pascals). Data evaluating the membrane is shown.

As can be seen from both Table 3 and Table 4, plateaus are observed after reaching 10 mM.

Tables 5 and 6 show the ESCA analysis of the membranes prepared.

As can be seen from Table 5, the carbon and oxygen percentages are relatively constant, although showing some variation. The nitrogen-to-carbon ratio can be used to measure the structure of the polyamide partition layer. This ratio eliminates the effect on the atomic percentage due to the varying amounts of water absorbed on the surface of the separator layer. Sulfur percentage is a direct measure of the percentage of aniline (3-thiol aniline) at the surface and ND represents an undetectable level of sulfur found in the control membrane.

Similarly, nitrogen is a measure of MPD exposed to the surface of the separator layer. For this analysis, when one nitrogen of the MPD residue is exposed, on average, the other half is estimated to be measured by the ESCA, ie the other half is exposed or the penetration depth of the ESCA Is in. Similarly, when sulfur is exposed, nitrogen from amide bonds is also exposed. Any errors due to some unacceptable percentages should be similar for both species. When considering the flow losses from Table 3 combined with the data from Table 5, for the highest concentrations of 3-thio aniline (eg 15 mM), 58% flow loss is due to 39% incorporation of 3-thiol aniline do. In addition, at an approximate saturation level (10 mM) of about 42% flow loss, 38% aniline is incorporated.

As can be seen from Table 6 and Table 4, Table 6 shows the saturation levels of both aniline incorporation and flow reduction. Table 6 shows the ratio of aniline to MPD of 11% (3-chloro aniline) and flow loss of 30%. The flow loss is, for example, the flow to the membrane when 1 mM 3-chloro aniline is applied from the flow (gfd) to the membrane when no 1 mM 3-chloro aniline is applied to obtain a flow reduction amount (gfd). Calculate by subtracting The flow loss is then equal to the percentage of flow reduction compared to the flow to the membrane without 3-chloro aniline applied. The calculation is shown below:

Flow (0 mM 3-chloro aniline)-Flow (1 mM 3-chloroaniline) = flow decrease

Flow Loss = 100 (Flow Decrease / Flow (0mM 3-chloroaniline)

At a saturation level of about 22% incorporation, there is a limited flow loss of 58%, which is the average of the flow losses for membranes coated with 5 mM, 10 mM and 15 mM 3-chloro aniline.

The ESCA provided in Table 6 also directly permits testing of atomic percentages. The saturation percentage of incorporated chlorine is about 1.3% and sulfur incorporation is 2%, and the degree of reaction is higher with 3-thio aniline than with 3-chloro aniline. The comparison of chlorine (Cl) or sulfur (S) to nitrogen (N) is important because surface contamination and water uptake affect carbon and oxygen atom percentages. By taking the ratio of Cl and S to N, surface contamination and excess carbon and oxygen in the water will not affect the ratio.

Example 4

BW30 membranes are obtained from FilmTec Corporation, Edina, Minnesota. BW30 membranes are MPD-polyamide membranes sold as BW30LE and BW30XLE. The formulation of MPD-polyamide membrane BW30XLE is modified by coating with a reactive modifying compound by the method of the present invention. In this example, the BW30 membrane is designated as the control.

1 and Tables 7-12 employ test solutions comprising an aqueous solution containing about 2,000 ppm NaCl, 5 ppm boric acid, 100 ppm isopropyl alcohol, and 100 ppm sodium nitrate at a trans-membrane pressure of 225 psi (1,551,320.39 Pascals). To provide data evaluating the prepared membrane.

1

As can be seen in FIG. 1, the IPA passage rates of some non-aromatic amines are close to 10-15%. However, these are uncoated controls, BW30 control membranes and BW30LE control membranes. The modified membrane has a relatively constant sodium nitrate passage rate with a low passage rate of 2.5%. In addition, the IPA passage rate for the membrane modified with 3-aminoacetophenone is 7%.

As can be seen from Table 7, aromatic disulfides behave similarly to standard halogenated anilines. 4-methoxy aniline and N-methyl versions are also similar to halogenated aniline. Three different modifications with large amounts of aliphatic properties and high mobility result in slight changes in performance in contrast to dimethoxy aniline, which indicates large flow changes and large improvements in solute passage.

As can be seen from Table 8, three anilines (3-amino acetophenone, m-phenetidine, ethyl 3-amino benzoate) show a substantial improvement in solute passage rate. These are anilines with aromatic amides, ketones, ethers and esters. Both morpholine and bis (2-methoxyethyl) amine show no substantial change in performance, although there is some improvement in solute passage rate with diether.

As can be seen from Table 9, the test compares the effects of different halogenated anilines and oxygen-containing aliphatic derivatives of aniline. As shown, 3 amino acetophenone, 3 methoxy aniline and 3,5 dimethoxy aniline demonstrate that reduced NaCl, IPA and sodium nitrate passage.

As can be seen from Table 10, a comparison of NaCl, sodium nitrate, borate (pH 8), and IPA passage rates for aniline and three aliphatic pendant modified membranes is provided. 3- (methyl thiol) aniline has a lower flow (10 gfd) and has a better borate pass rate of 29% to 43%, and a nitrate pass rate of 1.7% to 3.7%. Table 10 also shows a comparison of aliphatic amides with cyclic ethers or thiols. This is a comparison of morpholine and thiomorpholine. Morpholine modified membranes show lower solute passage, while thiomorpholine shows improved solute passage. Table 10 also shows the increased solute passage rate when 1,9 diamino nonane is used.

As can be seen from Table 11, the addition of 3-chloro aniline reduces the borate passage rate from 21.1 wt% to 16.5 wt% to a certain degree as the concentration increases. In addition, addition of 3-chloroaniline reduces the IPA passage rate from 7.18% to 5.96% by weight as the concentration increases. However, it was believed that the addition of increased concentrations of acetyl piperazine and 3-aminothiophenol did not significantly improve borate, nitrate or IPA passage rates. On the other hand, in the example of acetyl piperazine, keeping the concentration of acetyl piperazine low (i.e., 1 mM) results in a significantly greater nitrate passage rate than having a higher concentration of acetyl piperazine compared to the control in Table 10. Reduced.

As can be seen in Table 12, the use of piperazine as a binding group between phenyl groups has been found to improve solute passage. Table 12 has a comparison of 4-piperazin acetophenone and piperonyl piperazine for 3,4-methylenedioxy aniline, 3,5-dimethoxy aniline and 3-amino acetophenone. In both cases the percentage of tertiary amines leads to lower solute passage rates (piperonyl piperazine) or only slightly better solute passage rates (4-piperazine acetophenone). The flow is only slightly reduced when using 4-piperazine acetophenone (40 gfd vs. 41 gfd), but much lower than 3-amino acetophenone (19 gfd). As a modifying compound, piperonyl piperazine reduces the flow from 41 gfd to 25 gfd, and the flow is 29 gfd when using 3,4 methylenedioxy aniline.

Example 5

Membranes are prepared using a formulation for high-flow seawater membranes on a polysulfone porous substrate on a standard pilot coater as a continuous process at 13 feet per minute (fpm) (0.066 meters / second). First, a 3.5 wt% (wt.%) Solution of MPD is applied to a pre-fabricated polysulfone porous substrate in water. MPD application has a residence time of 156 seconds and excess MPD solution is removed using a nip roller. TMC dissolved in ISOPAR L is applied at a retention time of 132 seconds at 118 ml / ft ² . Polyamides are formed at the oil-water interface.

Thereafter, the oil is removed using an air knife and a pump. In some instances, the modifying compound is applied. A series of operations is performed at a concentration of 5 mM with 3-aminothiophenol, 3-chloroaniline, acetyl piperazine, amino crothenoic acid methyl ester, 3,5-dimethoxy aniline and 3-aminoacetophenone. The application rate of the modified compound is the same as that used for the TMC solution and has a residence time of 180 seconds. Excess modified compound is removed using an air knife and pump. The membrane is then passed through a room temperature water bath to remove excess oil and then through a 98 ° C. bath containing 3.5% glycerin. The residence time in the soaking bath is 37 minutes. The membrane is then dried for 10.6 minutes at a temperature of 95 ° C. through an air-floating dryer.

Table 13 shows the membrane names.

Membrane Name, Type, and Modification Compound Membrane name  Membrane Types and Modification Compounds RO-1  BW30XLE [FilmTec Corp., Edina, Minnesota] RO-2  BW30 Membrane (Film Tech Corporation of Edina, Minnesota) RO-3  Polyamide Membrane of the Invention Modified with 3-Aminothiophenol RO-4  Polyamide membrane of the present invention modified with 3-chloroaniline RO-5  Polyamide Membrane of the Invention Modified with Acetyl Piperazine RO-6  Polyamide Membrane of the Invention Modified with Amino Chroenoic Acid Methyl Ester RO-7  Polyamide Membrane of the Invention Modified with 3,5-dimethoxyaniline RO-8  Polyamide Membrane of the Invention Modified with 3-Aminoacetophenone NF  NF-200 Membrane (Film Tech Corporation of Edina, Minnesota)

In order to observe the biofilm formation efficacy on the surface of reverse osmosis (RO) and nano-filtration (NF) membranes, biofilm formation studies are performed in a rotating disk reactor (RDR) system. Three RDRs are used and nine (RO and NF) membrane swatches are attached onto the polycarbonate coupon with silicon rubber sealant in the RDR system. Table 14 shows the distribution of RO and NF membranes in different reactors.

Each reactor was run for 31 days. The feed to the reactor is biologically activated carbon (BAC) treated water. To enhance the increase in biofilm, nutrients (carbon: nitrogen: potassium) are added to the reactor. Glutamic acid, glucose, galactose and arabinose are used as carbon sources, potassium nitrate (KNO ₃ ) is used as the nitrogen source and potassium phosphate (K ₂ HPO ₄ ) is used as the potassium source. The carbon source, nitrogen source and potassium source were placed in a reactor at a molar ratio of 100: 10: 1 corresponding to 5.54 ml of carbon source, 16.88 ml of nitrogen source, and 4.00 ml of potassium source in a 20 liter vessel of nanopure water. Add. The flow rates of nutrients (C: N: P) and BAC treated water are 0.50 ml / min and 0.70 ml / min, respectively. Average culture-forming units / milliliters (CFU / ml) in BAC treated water are from 1.35 to about 1.9 × 10 ⁴ CFU / ml during the test. The reactor internal temperature is maintained at 25 ° C. throughout the test to negate the effect of temperature on biofilm increase and the ambient temperature also approaches 25 ° C. The rotational speed of the rotor in the RDR is 50 revolutions per minute (rpm) in all reactors.

RO and NF membranes in three RDR reactors are tested 31 days after operation using cryo and live / kill staining (L / D). Table 15 shows what analyzes were performed on each membrane.

The membrane is removed from the coupon using a sterile laser blade and a hemostatic agent without disturbing the surface of the membrane containing the biofilm. For membrane freeze-compartmentation analysis, Cryostate series # Leica CM 1850 was used and the thickness of each membrane piece was 5.0 μm.

LIVE / DEAD BacLight ^™ is used for live / kill staining of cells on the membrane surface. The kit contains SYTO 9 (3.34 mM) and propidium iodide (20 mM) dye. To stain the cells in the membrane, the same amount, 1.5 μl / ml of SYTO 9 and propidium iodide dye are diluted in 1 ml of Nanopure Water and after appropriate dilution, the dye is added to the top surface of the membrane and incubated for 1 hour. . After incubation, excess dye is washed away and the stained membrane is observed under an epifluorescence microscope (Microscope Series # Nikon, Eclipse E 800, Japan) at 100 × magnification.

For freeze-compartmentation analysis, 15 freeze-fragments are taken from each piece of 5 μm thick membrane and one line scan image of live and dead cells is taken. The values are then transformed into a data set using modified surface shape image analysis software. Each image provides different distributions of live and dead cells depending on the thickness of the biofilm on the membrane. To calculate the thickness at which live and dead cells occur in each image, the width is taken from the middle height. 2 shows a summary of freeze-compartmentation analysis of all membranes. Each bar for each membrane represents the average thickness (15 pieces of membrane) of live or dead cells.

2

As can be seen in Figure 2, on the surfaces of RO-1 and RO-7, the relative number of live cells is greater than the number of dead cells. In addition, when comparing the results of commercially available membranes, RO-1 and RO-2 with membranes with modified compounds, membranes with 3-amino acetophenone as modified compounds, RO-9 is one of the lowest number of dead cells And has the lowest number of live cells. The only other membrane that shows better cell number is the NF membrane.

Based on the thickness of the freeze-compartmented image, the approximate rate of accumulation of the biofilm can be calculated by equation 3:

Average increase in biofilm = average thickness of biofilm (μm) / duration of operation (days)

This analysis is simplified because the membrane biofilm is complex, heterogeneous and multi-mixed structure. However, Table 16 shows, in descending order of increasing, the average increase in biofilm for each membrane.

Based on freeze-compartmentation analysis and days of observation, the maximum mean increase in biofilm is shown to be less than 1 μm / day at the surfaces of membranes RO-6, RO-2, NF, and RO-8. In addition, from Table 16, it is shown that the bio-increase is reduced at the surface of the membrane when using 3-aminoacetophenone and 3-chloroaniline as the modifying compound.

Claims (22)

An aqueous coating composition comprising at least one polyfunctional compound is applied to at least a portion of the surface of the porous substrate to form a first coated substrate, wherein the polyfunctional compound is a polyfunctional amine, a polyfunctional alcohol, a polyfunctional thiol, and a polyfunctional Selected from functional anhydrides); An organic solvent composition comprising an organic solvent and one or more of a polyfunctional acid halide, a polyfunctional anhydride and a polyfunctional dianhydride is applied to the first coated substrate to form a discriminating layer over at least a portion of the surface of the porous substrate. Wherein the separation layer comprises a reaction product of the polyfunctional compound with one or more of the polyfunctional acid halide, the polyfunctional anhydride and the polyfunctional dianhydride, and the residual reactive moiety, wherein the residual reactive moiety is the polyfunctional Of compounds, polyfunctional acid halides, polyfunctional anhydrides, polyfunctional dianhydrides, hydrolysis products of polyfunctional compounds, hydrolysis products of polyfunctional acid halides, hydrolysis products of polyfunctional anhydrides, and hydrolysis products of polyfunctional dianhydrides One or more of the unreacted functional groups); The modified composition is applied to at least a portion of the surface of the separator layer to form a modified separator layer, wherein the modified composition comprises an organic solvent and a reactive modifying compound comprising functional groups, wherein the modified composition comprises at least a surface of the separator layer. Disposed on a portion to form a modified composition layer fixed to the separation layer by one or more of hydrogen bonding, ionic bonding, covalent bonding, physical entanglement, and chemical bonding. The method of claim 1, wherein the functional groups included in the reactive modifying compound react with the separating layer to fix the modifying composition layer to the separating layer through chemical bonding. Wherein the chemical bond is selected from amines, amides, sulfamides, urethanes, ureas, thioesters, esters, aminoesters, imides, and amines including secondary, tertiary, quaternary and beta hydroxyl amines. Manufacturing method. The process of claim 1, wherein the functional group is selected from the group consisting of esters, thioesters, ethers, alcohols, anhydrides, epoxides, acid halides, isocyanates and 2-oxazolines. The method of claim 1, wherein the functional group is selected from the group consisting of thiols, thiophenols, sulfides and disulfides. The method of claim 1, wherein the functional group is selected from the group consisting of azide, amine, aminoalcohol and aminoester. The method of claim 5, wherein the functional group is an amine and is selected from derivatives of aniline that are not reactive modifying compounds. The method of claim 6, wherein the reactive modifying compound comprises a pendant functional group selected from the group consisting of halides and thiols. The method of claim 7, wherein the reactive modifying compound comprises a pendant functional group, the functional group is an amine, and the reactive modifying compound is selected from compounds of the following structural formula.

The method of claim 1, wherein the reactive modifying compound comprises a pendant functional group selected from the group consisting of aliphatic amines and aromatic amines. The method of claim 1, wherein the reactive modifying compound comprises a pendant functional group selected from the group consisting of esters, ketones, thioesters, amides, sulfamides, alcohols and ethers. The method of claim 1, wherein the reactive modifying compound comprises a pendant functional group selected from the group consisting of thiols, sulfides, disulfides, aldehydes and thiophenols. The method of claim 1, wherein the reactive modifying compound comprises a pendant functional group selected from the group consisting of halogens. The method of claim 1, wherein the reactive modifying compound comprises a pendant functional group selected from the group consisting of organometallic compounds and metal complexes. A porous substrate having a first side parallel to the second side; And A multilayer film comprising a modified separator layer comprising an inner side and an outer side, Wherein the inner face is in operative contact with at least one face of the porous substrate, wherein the outer face and a portion of the modified separator layer disposed between the inner face and the outer face Includes a plurality of pendant functional groups connected by one or more of hydrogen bonds, ionic bonds, covalent bonds, physical entanglements, and chemical bonds to the modified separator layer, wherein the chemical bonds are amide, sulfamide, urethane, urea , At least one of amines including thioesters and secondary amines, tertiary amines, quaternary amines and beta hydroxyl amines. The multilayer film of claim 14, wherein the pendant functional group is selected from the group consisting of aliphatic amines and aromatic amines. The multilayer membrane of claim 14, wherein the pendant functional group is selected from the group consisting of esters, ketones, thioesters, amides, sulfamides, alcohols and ethers. The multilayer membrane of claim 14, wherein the pendant functional group is selected from the group consisting of thiols, sulfides, disulfides and thiophenols. 15. The multilayer film of claim 14 wherein the ratio of residues derived from pendant functional groups in the region close to the outer surface of the separator layer, relative to the region close to the inner face of the separator layer, is approximately 1.5: 1. . The multilayer membrane of claim 14, wherein the modified separator layer provides a membrane having a higher rejection rate. 20. The multilayer membrane of claim 19, wherein the modified separator layer provides a membrane having a higher removal rate of solutes comprising at least one of nitrate, silica, boric acid, arsenic, and selenium and metal salts. The multilayer of claim 19, wherein the modified separator layer provides a membrane with a higher removal rate of small organics comprising one or more of alcohols, disinfection by-products, halogenated solvents, agents, and endocrine disruptors. membrane. The multilayer membrane of claim 14, wherein the modified separator layer provides a membrane with improved bio-increasing inhibitory properties.